Commit 8234177d authored by Nikunj A Dadhania's avatar Nikunj A Dadhania Committed by Borislav Petkov (AMD)
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virt: sev-guest: Remove is_vmpck_empty() helper 



Remove is_vmpck_empty() which uses a local array allocation to check if the
VMPCK is empty and replace it with memchr_inv() to directly determine if the
VMPCK is empty without additional memory allocation.

  [ bp: Massage commit message. ]

Suggested-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarNikunj A Dadhania <nikunj@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250106124633.1418972-2-nikunj@amd.com
parent 21fc6178

drivers/virt/coco/sev-guest/sev-guest.c

+2 −12
Original line number Diff line number Diff line
@@ -63,16 +63,6 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. 
/* Mutex to serialize the shared buffer access and command handling. */

static DEFINE_MUTEX(snp_cmd_mutex);



static bool is_vmpck_empty(struct snp_msg_desc *mdesc)

{

	char zero_key[VMPCK_KEY_LEN] = {0};



	if (mdesc->vmpck)

		return !memcmp(mdesc->vmpck, zero_key, VMPCK_KEY_LEN);



	return true;

}



/*

 * If an error is received from the host or AMD Secure Processor (ASP) there

 * are two options. Either retry the exact same encrypted request or discontinue
@@ -335,7 +325,7 @@ static int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r 
	guard(mutex)(&snp_cmd_mutex);



	/* Check if the VMPCK is not empty */

	if (is_vmpck_empty(mdesc)) {

	if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) {

		pr_err_ratelimited("VMPCK is disabled\n");

		return -ENOTTY;

	}
@@ -1024,7 +1014,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) 
	}



	/* Verify that VMPCK is not zero. */

	if (is_vmpck_empty(mdesc)) {

	if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) {

		dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id);

		goto e_unmap;

	}